1. Field of the Invention
The present invention relates to a fuel injection controller applied to a fuel injection device of an internal combustion engine having a pressure accumulation chamber that accumulates fuel in a high-pressure state and that supplies the fuel to injectors, a fuel pump that pressure-feeds the fuel to the pressure accumulation chamber through reciprocating motion of multiple plungers, and a sensor that senses the fuel pressure in the pressure accumulation chamber, the fuel injection controller having a control device that controls the sensed fuel pressure to target fuel pressure by operating the fuel pump.
2. Description of Related Art
A known fuel injection device of this kind has a common pressure accumulation chamber (common rail) for supplying high-pressure fuel to injectors of respective cylinders of a diesel engine, for example, as described in JP-A-S62-258160. The common rail diesel engine can freely set a target value of the fuel pressure (target fuel pressure) in the common rail in accordance with an operation state of the engine and can freely control the fuel pressure supplied to the injectors.
A fuel injection controller performs open control of deciding an operation amount of a fuel pump based on the operation state of the engine or feedback control of deciding the operation amount of the fuel pump based on a difference between the fuel pressure in the common rail sensed by a fuel pressure sensor and the target fuel pressure to make the fuel pressure in the common rail follow the target fuel pressure.
However, controllability of the fuel pressure is deteriorated if an abnormality is caused in either one of multiple pressure-feeding systems that pressure-feed the fuel to the common rail with multiple plungers of the fuel pump respectively. The fuel injection controller performing only the open control sets the operation amount of the fuel pump on an assumption that all the pressure-feeding systems are normal. Accordingly, a fuel amount pressure-fed to the common rail falls short and the fuel pressure decreases when the abnormality is caused. As for the fuel injection controller performing the feedback control, the controllability of the fuel pressure is deteriorated due to a response delay in the feedback control immediately after the abnormality is caused. As for the fuel injection controller that performs both of the open control and the feedback control to improve the following performance of the fuel pressure to follow the target fuel pressure and control stability during a transitional period, the open control for improving the following performance during the transitional period cannot function normally because of the abnormality in the pressure-feeding system. As a result, the controllability is deteriorated.